1. Field of the Invention
The present invention relates to a vehicular transmission, and more particularly to the structure of a vehicular transmission that is equipped with a reverse function.
2. Description of the Background Art
It is well known to provide a vehicle transmission that is capable of reversing the output of the engine. JP-A No. 306646/2004 discloses a vehicle having a transmission equipped with a reverse function. In this disclosure a driven gear to which engine power is inputted, and a drive gear for outputting the engine power, are integrally provided on a reverse idle shaft. The engine power that is inputted to the driven gear of the reverse idle shaft from a counter shaft is transmitted from the drive gear to a drive shaft at the time of reverse traveling motion.
FIGS. 4 and 5 are sectional views showing the construction of a conventional reverse idle gear. In the example of FIG. 4, a drive gear 51 for outputting engine power is spline-coupled to a sleeve portion 53 of a driven gear 52 to which the engine power is inputted. In the example of FIG. 5, a driven gear 55, to which engine power is inputted, is formed integrally with a drive gear 54 for outputting the engine power.
In the prior art as described above, back torque inputted to the drive shaft from the drive wheels is transmitted to the reverse idle gear without being reduced. Accordingly, the prior art configurations are subject to the technical problem in which the portions around the reverse idle gear must be imparted with a strength that is sufficient to withstand the back torque, leading to an increase in the size or weight of the transmission.
It is an object of the present invention to solve the above-mentioned problem of the prior art and to provide a vehicular transmission having a structure capable of reducing an inputted back torque without leading to an increase in the size or weight of the transmission.